The National Centers for Coastal Ocean Science, Thunder Bay National Marine Sanctuary and Great Lakes Environmental Research Laboratory will map 50-100 square kilometers of the lakebed in Thunder Bay National Marine Sanctuary. The purpose of the mission is to collect new lakebed bathymetry, backscatter and underwater imagery to characterize and map natural and cultural resources. Data will be collected from the NOAA research vessel Storm using a hull-mounted Kongsberg 2040C multibeam echosounder and a towed Klein 3000 sidescan sonar system. Survey dates are tentatively set from July 22 to August 2, 2019. A separate mission scheduled for September 9-20 will focus on collecting in-situ groundtruth imagery using a drop camera in the same general mapping area. Collected data will provide a digital elevation model of the lakebed, and maps of geomorphological features, substrates, habitats, and benthic species. This project builds off of similar mapping work in Lake Michigan off the coast of Wisconsin and many existing surveys in the sanctuary.